Research on Iceberg B-15A (Image 5)

Research on Iceberg B-15A (Image 5) The northern edge of the giant iceberg B-15A, located close to Ross Island, Antarctica. Iceberg B-15A is a fragment of a much larger iceberg (B-15) that broke away from the Ross Ice Shelf in March 2000. Scientists believe that the enormous piece of ice broke away as part of a long-term natural cycle (every 50-to-100 years, or so) in which the shelf--which is roughly the size of Texas--sheds pieces much as human fingernails grow and break off. Researchers have placed global positioning systems (GPS), weather monitoring stations and four seismometers on different icebergs to track them. The goal is to learn more about what causes icebergs to calve, how and why they drift, what happens when the icebergs warm, and why they are producing previously unknown tremors that are picked up on seismometers as far away as Tahiti. Plans are to track B-15A until it disintegrates. [Iceberg Update: In 2005 prevailing currents took B-15A slowly past the Drygalski ice tongue (an iceberg located in northern McMurdo Sound); the collision broke off the tip of Drygalski in mid-April. Iceberg B-15A sailed on along the coast leaving McMurdo Sound until it ran aground off Cape Adare in Victoria Land (a region of Antarctica lying south of New Zealand), where it broke into several smaller pieces on Oct. 27 and 28, 2005. The largest piece is still named B-15A (its surface is now approx. 1700 kilometers2), while three additional pieces were named B-15P, B-15M and B-15N. It has since moved farther up north and broken up into more pieces. These were spotted by air force fisheries patrol on Nov. 3, 2006. On November 21, several large pieces were seen just 60 kilometers off the coast of Timaru, New Zealand, the largest measuring about 1.8 kilometers wide and 120 feet high.] (Date of Image: Jan. 29, 2001) [One of 8 related images. See Next Image .]